Process for the improvement of natural wood, particularly for the production of compressed wooden components provided if required with ornamentation

ABSTRACT

A process for producing compressed wooden components provided if required with ornamentation, comprising the operations of immersing the natural initial wood in an aqueous bath containing pyridene, then drying the wood to a residual moisture content of 12-16 percent and finally compressing the pretreated wood under the simultaneous action of heat at a temperature of about 180* C. During hot compression the desired ornamentation may be impressed by means of a mold corresponding to the negative of the ornamentation. Vacuum may be applied during this operation. Alternatively the wood pretreated by the water-pyridene bath may be first compressed into a panel with plane faces and this panel may be successively further compressed in a mold for impressing the ornamentation.

Elite iatea atent 3,621,897 1 72] Inventors Luigi VEIZZOIH; 56]References Cited 2 I A l N ()lltllel, b02111 Oli Pordenone, lltalyUNITED STATES PATENTS or f; 1M. 1970 1,899,411 2/1933 Fletcher 144/328 x[45] Patented Nov 197] 2,414,808 1/1947 Hamill t 144/327 [73] AssigneeJoseph M 3 3282.313 11/1966 Schuerch 144/327 Valdaora (Bolzano), ltalyPrimary Examiner- Donald R. Schran a part interest Anorney- Waters,Roditi, Schwartz & Nissen I 32] Priorities Mar. 6, 1969 1331 lltaly [31]13748-A/69; ABSTRACT: A process for producing compressed wooden June 1119 9 m ML 18070 A/69 components provided if required with ornamentation,comprising the operations of immersing the natural initial wood in w anaqueous bath containing pyridene, then drying the wood to 54] PROCESSlFOlR THE IMPROVEMENT 0F a residual moisture content of 12-16 percentand finally com- NATURAL WOOD, PARTICULARLY FOR THE pressing thepretreated wood under the simultaneous action of PRODUCTKON OFCOMPRESSED WOODEN heat at a temperature of about 180 C. During hotcompres- COMIPONIENTS PROVIDED IF REQUIRED WITH sion the desiredornamentation may be impressed by means of ORNAMENTATION a moldcorresponding to the negative of the ornamentation. 10 Claims,3 DrawingFigs. Vacuum may be applied during this operation. Alternatively 52 Ithe wood pretreated by the water'pyridene bath may be first Us c 34 12compressed into a panel with plane faces and this panel may [5 1] mm ClB27" 1/00 be successively further compressed in a mold for impressing501 Field of seal-c1. 144/327,

PROCESS FOR THE IMPROVEMENT OF NATURAL WOOD, PARTICULARLY FOR THEPRODUCTION OF COMPRESSED WOODEN COMPONENTS PROVIDED IF REQUIRED WllTI-IORNAMENTATION The present invention relates to a process for theimprovement of natural wood, particularly for the production ofcompressed wooden components provided if required with omamentation onat least one side.

in the present description the term natural wood" wood which presentsits natural graining. Hence it does clude' wooden fibers, shavings orchips.

However it should be noted that the natural wood used for obtaining thecomponents according to the process of the invention may comprise asingle piece or a number of pieces or layers which present their naturalgraining and which have a moisture content of about 16 percent. The termimprove ment means a treatment for natural wood which leads to anincreased density and higher specific gravity of the wood and a greatersurface resistance to wear.

The wooden components produced according to the invention areparticularly suitable for flooring (parquet) and in general as amaterial which because of its use requires a high specific gravity withexcellent surface resistance to wear. In the case of shaped decorativewooden components provided with a determined ornamentation on at leastone side, these components may be usefully employed in the manufactureof furniture.

It is well known that natural wood possesses a very low plasticity andcompressibility.

The obtaining of shaped decorative components has already been tried byexploiting the deformability of wood under the simultaneous action ofheat, pressure and humidity. According to this known method the naturalhumidified wood is placed in an open die and subjected to compressionand the simultaneous action of heat. However this method does not givethe desired results and does not lead to an improvement in the wood.Only small depths of deformation can be obtained (maximum 5 mm.) forcreating the decorative omamentation and even with these smalldeformations cracks are formed in the wood. The temperatures used inthis method are relatively low and compression times relatively long.The deformations obtained are not perfectly irreversible and have edgeswhich are smooth and round rather than sharp, and the wood darkensbecause of the heat applied during compression. Shaped decorative woodencomponents have consequently been produced up to now mainly by curvingpieces of solid natural wood by exploiting its flexibility or bymachining with the removal of shavings (carving, turning, milling thesolid wood, etc.) or by compressing a plurality of veneer sheets inmolds, or by applying a combination of these various working methods.

On the other hand in the production of wooden fiber panels from woodenfiber it is known that by heating the fibrous mass in the presence ofdetermined quantities of water and simultaneously applying strongcompression in a closed mold, a hot plasticization is obtained becauseof a series of chemical processes, and practically a new material iscreated. Initiation of the chemical reactions is however stronglyhindered and sometimes prevented by the presence of air in the pores ofthe fibrous mass. The chemical reactions which take place in the courseof this process comprise substantially a first phase mainly ofhydrolysis and a successive phase mainly of condensation during whichresinous bodies are formed with hydrophobe and adhesive characteristicswhich make strong irreversible deformations possible, because of theirthermoplasticity.

The object of the invention is that of permitting the production ofimproved wooden components provided if required with ornamentation, frompieces of wood which present their natural grain in order to obtainwooden components with a high specific gravity and excellent surfaceresistance to wear, comprising, if required,, irreversible decorativedeformations even of considerable depth and a large degree of edgedefini- IlOn.

means not in- This object is attained according to the invention by amethod which comprises a hot compression treatment of the humidifiedinitial natural wood in which the initial wood, before being subjectedto said hot compression treatment, is immersed in a water bathcontaining pyridine and is successively dried to a residual moisturecontent of approximately l2-l6 percent, after which it undergoescompression at a temperature of about C.

The water bath used for immersion of the natural wood consistspreferably of 3 parts by weight of water and 1 part by weight ofpyridine (C H N). The time of immersion of the wood in this bath mayvary and it is in the order of some minutes, for example about 5minutes. The impregnated wood is then removed from the bath andintroduced into a drying chamber in which hot air circulates at atemperature of about 60-80 C. This circulating air is made to passthrough a condenser in order to condense any excess water-pyridinemixture. The wood remains in the drying chamber for that time necessaryto reduce its moisture content to about l2l 6 percent. In this conditionthe wood is without odor.

This pretreatment of the wood with the water-pyridine mixture has beenfound to be very efficient in the sense of favor ing priming andprogress of the hydrolysis phase which the wood undergoes during thesuccessive compression treatment at the temperatures used (about 180 C).it is found in fact that because of the presence of the pyridine in thepretreated wood, the hydrolysis phase begins almost immediately when thewood is subjected to compression and the simultaneous action of heat.Compression of the wood can be carried out in successive stages. In afirst compression phase the hydrolysis begins. After a certain time,which depends upon the thickness of the wood, further compression iscarried out and the polycondensation phase of the already hydrolyzedwood begins. Even if cracks or breakages in the wood are formedfollowing compression, these are completely eliminated in this phase inwhich a resinous homogeneous body is formed with hydrophobecharacteristics on which the natural grain of the piece or pieces ofwood initially used remains visible. Because of the short duration ofhot compression treatment, the wood does not undergo strong coloring.

If the hot compression of the pretreated wood is carried out simplybetween the faces of a press, wooden panels with plane faces areobtained which after planing the face which will remain in view, can bedirectly used, for example for flooring.

These panels have an excellent surface resistance to wear and a highspecific gravity. The process can thus be used to considerably improvethe characteristics of the initial natural wood, and makes the use ofless valuable woods possible for those uses for which these woods wouldnot otherwise be suitable.

The hot compression of the pretreated wood can also be carried out in apress in which at least one face carries a mold with the profilecorresponding to the negative of an ornamentation which it is requiredto impress on the wood. In this manner it is possible to directly obtainshaped decorative components provided on at least one side withornamentation having well-defined edges, with irreversible deformationseven of considerable depth and presenting the natural grain of theinitial wood. In order to diminish the coloring which the wood undergoesunder hot compression and to further favor the initiation of thechemical reactions which take place during this process, it may beadvisable to carry out the hot compression under vacuum (about 650 mm.Hg) so as to eliminate the air contained in the mold and the pores ofthe wood.

Another method provided by the invention for producing decorative-shapedcomponents and which has been found particularly convenient in the casein which it is required to obtain particularly deep and well-definedornamentations, consists of first forming precompressed panels with flatfaces as described above, then introducing these panels after suitableplaning on the side or sides which will be visible, between the faces ofa press, at least one of whose faces carries a mold whose profilecorresponds to the negative of the ornamentation required, and to carryout a further compression under the simultaneous action of heat.Proceeding in this manner it is found that it is possible to impressdecorative ornamentations of greater depth on the wood, having perfectlydefined edges.

It should be noted that according to the process described it is alsopossible to build up the compressed or decorative component from anumber of layers of wood superimposed horizontally, for example usingfor the face in view a type of wood more valuable than for the internallayers. Said layers can also be side by side vertically. Even if thecomponent is made from a number of horizontal or vertical layers, aperfect and durable joining together of the various layers isnevertheless obtained.

The practical execution of the process according to the invention fordirectly producing in a single hot compression operation thedecorative-shaped components is described hereinafter, by way ofexample, with reference to the accompanying drawing in which:

FIGS. 1-3 show very diagrammatically a mold in three successive phasesof the process.

The drawing shows two faces of a press which are heated (in anyconventional method, not illustrated), namely a lower face I and anupper face 2. On the lower face 1 rests a base plate 3 of steel whichcomprises a raised ornamentation 4 opposite the resting side,corresponding to the negative ofthe ornamentation which it is requiredto impress on the wood. The plate 3 further comprises a raised edge 5which surrounds the zone containing the ornamentation 4.

A silicone ring 6 rests on the face 1 and surrounds the entire plate 3.Finally, the mold comprises an upper plate 7 of aluminum resting on thering 6 and on which the upper face 2 of the press will rest.

As seen in FIG. I the piece of wood 8 prepared as described above(immersed in the water-pyridine mixture and dried to a residual moisturecontent of about l216 percent) is placed on the edge 5 of the plate 3before resting the upper plate 7 on the silicone ring 6.

This latter is provided with a connection 9 for connecting the spaceformed by the plates 3 and 7 and the ring 6 to a vacuum pump which isnot illustrated. When the mold is prepared as illustrated in FIG. I, thevacuum is created (about 650 mm. Hg) in order to eliminate the air fromsaid space and from the pores in the wood 8.

Following this, a first compression phase is carried out by making thefaces I and 2 of the press approach each other (see FIG. 2) and causingpartial copenetration of the piece of wood 8 and the baseplate 3. Inthis phase the vacuum previously created inside the mold is maintainedand hydrolysis of the wood begins. After a certain time furthercompression is carried out and at the end of it (see FIG. 3) the upperplate 7 of aluminum is brought to rest on the edge 5 of the lower plate3 so arresting the path of approach of the faces of the press andhermetically closing the inside of the mold. At this point the vacuumpump may be stopped. By this operation the complete isolation of thealready hydrolyzed wood from the atmosphere is obtained and thepolycondensation phase begins.

As clearly seen in FIG. 3, by completely closing the mold the piece ofwood becomes perfectly adapted to the baseplate, thus taking its shape.The part of the wood outside the edge 5 constitutes scrap in this case,while the decorative-shaped component is formed from the piece of woodwhich is inside said edge.

It should be observed that the wood undergoes no sensible coloringduring said treatment because of the short time in the heated mold. Thistime of residence is, for example, in the order of 60-80 seconds for adepth of ornamentation up to about 12 mm. and heating to 185 C.

It should be noted that in the process according to the inventionneither binder nor adhesive additives are used on the wood.

As has been stated previously, the application of vacuum during the hotcompression operation is not indispensable Thus, in the apparatus shownin the drawing, the silicone ring 6 and the connection 9 for connectingto the vacuum pump can be dispensed with.

The same apparatus can be used for the production of shaped decorativecomponents starting from already precompressed panels which in theirturn can be prepared using the press with its lower face I and upperface 2 without the mold constituted by the plates 3 and 7.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A process for the improvement of natural wood, particularly for theproduction of compressed wooden components provided if required withornamentation, comprising hot compression treatment of the humidifiedinitial natural wood, in which the initial wood, before being subjectedto said hot compression treatment, is immersed in an aqueous bathcontaining pyridine, and is successively dried to a residual moisturecontent of about 12-16 percent, after which it is compressed at atemperature of about I C.

2. A process as claimed in claim 1, in which the natural wood isimmersed for some minutes in a bath consisting of 3 parts by weight ofwater and 1 part by weight of pyridine.

3. A process as claimed in claim I, in which the wood impregnated by theaqueous bath containing pyridine is dried by means of hot air at atemperature of about 60-80 C., from which the excess water-pyridinemixture is continually eliminated.

4. A process as claimed in claim 1, in which the wood prepared with thewater-pyridine mixture which is subjected to hot compression comprises asingle piece.

5. A process as claimed in claim I, in which the wood prepared with thewater-pyridine mixture which is subjected to hot compression comprises anumber of pieces, preferably disposed as layers, superimposedhorizontally or side by side vertically.

6. A process as claimed in claim I, in which the hot compression of thewood prepared with the water-pyridine mixture is carried out in a numberof successive stages with intermediate intervals.

7. A process as claimed in claim I, in which the wood prepared with thewater-pyridine mixture is hot compressed between the faces of a pressand the compressed panel obtained is planed on that face ofit which willbe in view.

8. A process as claimed in claim 7, in which the compressed panel planedon the face or faces which will be in view is introduced between thefaces of a press, at least one of which faces carries a mold whoseprofile corresponds to the negative of an ornamentation to be impressedon the compressed panel, and a further compression is carried out insaid press under the simultaneous action of heat.

9. A process as claimed in claim 1, in which the wood prepared with thewater-pyridine mixture is hot compressed in a mold of which at least oneinternal surface has a profile corresponding to the negative of anornamentation to be impressed on the wood.

10. A process as claimed in claim 9, in which during the hot compressionof the wood prepared with the water-pyridine mixture, the inside of themold is put under vacuum.

2. A process as claimed in claim 1, in which the natural wood isimmersed for some minutes in a bath consisting of 3 parts by weight ofwater and 1 part by weight of pyridine.
 3. A process as claimed in claim1, in which the wood impregnated by the aqueous bath containing pyridineis dried by means of hot air at a temperature of about 60*-80* C., fromwhich the excess water-pyridine mixture is continually eliminated.
 4. Aprocess as claimed in claim 1, in which the wood prepared with thewater-pyridine mixture which is subjected to hot compression comprises asingle piece.
 5. A process as claimed in claim 1, in which the woodprepared with the water-pyridine mixture which is subjected to hotcompression comprises a number of pieces, preferably disposed as layers,superimposed horizontally or side by side vertically.
 6. A process asclaimed in claim 1, in which the hot compression of the wood preparedwith the water-pyridine mixture is carried out in a number of successivestages with intermediate intervals.
 7. A process as claimEd in claim 1,in which the wood prepared with the water-pyridine mixture is hotcompressed between the faces of a press and the compressed panelobtained is planed on that face of it which will be in view.
 8. Aprocess as claimed in claim 7, in which the compressed panel planed onthe face or faces which will be in view is introduced between the facesof a press, at least one of which faces carries a mold whose profilecorresponds to the negative of an ornamentation to be impressed on thecompressed panel, and a further compression is carried out in said pressunder the simultaneous action of heat.
 9. A process as claimed in claim1, in which the wood prepared with the water-pyridine mixture is hotcompressed in a mold of which at least one internal surface has aprofile corresponding to the negative of an ornamentation to beimpressed on the wood.
 10. A process as claimed in claim 9, in whichduring the hot compression of the wood prepared with the water-pyridinemixture, the inside of the mold is put under vacuum.